Organic light emitting display apparatus and method of manufacturing organic light emitting display apparatus

ABSTRACT

An organic light emitting display (OLED) apparatus and a method of manufacturing the same, the OLED apparatus including: a substrate; an active layer formed on the substrate; a gate electrode insulated from the active layer; source and drain electrodes insulated from the gate electrode and electrically connected to the active layer; a pixel defining layer formed on the source and drain electrodes, having an aperture to expose one of the source and drain electrodes; an intermediate layer formed in the aperture and comprising an organic light emitting layer; and a facing electrode which is formed on the intermediate layer. One of the source and drain electrodes has an extension that operates as a pixel electrode. The aperture exposes the extended portion. The intermediate layer is formed on the extended portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/464,653, filed on May 4, 2012, which is a divisional of U.S. patentapplication Ser. No. 12/510,547, filed on Jul. 28, 2009, now issued asU.S. Pat. No. 8,207,662, and claims priority from and the benefit ofKorean Patent Application No. 10-2008-0081069, filed on Aug. 19, 2008,all of which are hereby incorporated by reference for all purposes as iffully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Aspects of the present invention relate to an organic light emittingdisplay (OLED) apparatus and a method of manufacturing the OLEDapparatus.

2. Description of the Related Art

Many current electronic devices include a thin, flat-panel displayapparatus. Such flat-panel display apparatuses can be classified asorganic or inorganic light emitting display apparatuses, which areself-emitting display apparatuses that are regarded as next generationdisplay apparatuses, due to having wide viewing angles, excellentcontrast, and fast response speeds. Organic light-emitting displayapparatuses, which include light emitting layers formed of an organicmaterial to display various colors, have improved luminance, reduceddriving voltages, and higher response speeds, in comparison to theinorganic light emitting display apparatuses.

An organic light emitting display apparatus includes an organic lightemitting diode, in which cathode and anode electrodes are formedadjacent to an organic light emitting layer. When a voltage is appliedto the cathode and anode electrodes, the organic light emitting layer,which is connected to the cathode and anode electrodes, generatesvisible light.

An organic light emitting display apparatus includes a plurality of thinfilms, which are precisely patterned. A large number of processes areperformed, in order to form such patterns. The patterns may be formed byusing various methods, such as photolithography using a mask.

Photolithography should be precisely controlled. Also, variousoperations, such as photo resist formation, exposure, developing, andetching are performed to form a pattern using a mask. Thus, suchphotolithography methods are complicated time consuming and aredifficult to control, which can result in the production of a largenumber of defects. Also, the total thickness of an organic lightemitting display apparatus produced by such processes is relativelythick, due to the multitude of stacked films.

SUMMARY OF THE INVENTION

Aspects of the present invention provide an organic light emittingdisplay (OLED) apparatus that is relatively thin and simple tomanufacture, and a method of manufacturing the OLED apparatus.

According to an aspect of the present invention, there is provided anorganic light emitting display (OLED) apparatus including: a substrate;an active layer formed on the substrate; a gate electrode that isinsulated from the active layer; source and drain electrodes that areinsulated from the gate electrode and electrically connected to theactive layer; a pixel defining layer formed on the source and drainelectrodes, which include an aperture to expose one of the source anddrain electrodes; an intermediate layer that is formed in the apertureand includes an organic light emitting layer; and a facing electrodethat is formed on the intermediate layer. One of the source and drainelectrodes has an extended portion and can thereby operate as a pixelelectrode. The aperture exposes the extended portion, and theintermediate layer is connected thereto, through the aperture.

According to aspects of the present invention, the pixel defining layermay be formed of an inorganic material.

According to aspects of the present invention, an overcoat film may beformed on the gate electrode, to insulate the gate electrode from thesource and drain electrodes. The source and drain electrodes may beformed on the overcoat film.

According to aspects of the present invention, the OLED apparatus mayfurther include a spacer formed on the pixel defining layer, so as toexpose the aperture. The facing electrode may be formed above the pixeldefining layer.

According to aspects of the present invention, the OLED apparatus mayfurther include: a first capacitor electrode, which is formed in thesame plane and of the same material as the active layer; and a secondcapacitor electrode that is insulated from the first capacitor electrodeand is formed on the first capacitor electrode, in the plane and fromthe same material as the gate electrode, so as to correspond to thefirst capacitor electrode.

According to aspects of the present invention, the first and secondcapacitor electrodes may be formed below the pixel electrode.

According to another aspect of the present invention, there is provideda method of manufacturing an organic light emitting display (OLED)apparatus, the method including: forming an active layer on a substrate;forming a gate electrode, so as to be insulated from the active layer;forming source and drain electrodes, so as to be insulated from the gateelectrode and be electrically connected to the active layer; forming apixel defining layer on the source and drain electrodes, which includesan aperture to expose one of the source and drain electrodes; forming anintermediate layer, which includes an organic light emitting layer, inthe aperture; and forming a facing electrode on the intermediate layer.The forming of the source and drain electrodes includes forming anextended portion on one of the source and drain electrodes, such that itoperates as a pixel electrode. The forming of the pixel defining layerincludes forming the aperture such that it exposes the extended portion.The forming of the intermediate layer includes connecting theintermediate layer to the pixel electrode, through the aperture.

According to aspects of the present invention, the forming of the sourceand drain electrodes and the pixel defining layer may be performed usinga single halftone mask.

Additional aspects and/or advantages of the invention will be set forthin part in the description which follows and, in part, will be obviousfrom the description, or may be learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will becomeapparent and more readily appreciated from the following description ofthe exemplary embodiments, taken in conjunction with the accompanyingdrawings, of which:

FIG. 1 is a schematic cross-sectional diagram of an organic lightemitting display (OLED) apparatus, according to an exemplary embodimentof the present invention;

FIG. 2 is an enlarged view of portion A of FIG. 1;

FIGS. 3 through 13 are schematic cross-sectional diagrams sequentiallyshowing a method of manufacturing the OLED apparatus of FIG. 1,according to an exemplary embodiment of the present invention; and

FIG. 14 is a schematic cross-sectional diagram of an OLED apparatus,according to another exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Reference will now be made in detail to the exemplary embodiments of thepresent invention, which are illustrated in the accompanying drawings,wherein like reference numerals refer to like elements throughout. Theexemplary embodiments are described below, in order to explain theaspects of the present invention, by referring to the figures.

As referred to herein, when a first element is said to be disposed orformed “on”, or “adjacent to”, a second element, the first element candirectly contact the second element, or can be separated from the secondelement by one or more other elements located therebetween. In contrast,when an element is referred to as being disposed or formed “directly on”another element, there are no intervening elements present. As usedherein, the term “and/or” includes any and all combinations of one ormore of the associated listed items.

FIG. 1 is a schematic cross-sectional diagram of an organic lightemitting display (OLED) apparatus 100, according to an exemplaryembodiment of the present invention. FIG. 2 shows portion A of FIG. 1.Referring to FIG. 1, the OLED apparatus 100 includes a substrate 101, anactive layer 103, a gate electrode 105, a source electrode 107, a drainelectrode 108, a pixel defining layer 109, a spacer 111, an intermediatelayer 112, and a facing electrode 113.

The substrate 101 may be formed of a transparent glass material mainlycontaining SiO₂. However, the substrate 101 is not limited thereto andmay be formed of a transparent plastic material, for example. Theplastic material may be an organic material selected from the groupconsisting of polyethersulphone (PES), polyacrylate (PAR),polyetherimide (PEI), polyethyelenen napthalate (PEN),polyethyeleneterepthalate (PET), polyphenylene sulfide (PPS),polyallylate, polyimide, polycarbonate (PC), cellulose triacetate (TAC),and cellulose acetate propionate (CAP), for example.

If the OLED apparatus 100 is a bottom emission-type, in which an imageis projected through the substrate 101, the substrate 101 is formed of atransparent material. However, if the OLED apparatus 100 is a topemission-type, in which an image is projected away from the substrate101, the substrate 101 may be formed of an opaque or semi-transparentmaterial, such as a metal. If the substrate 101 is formed of a metal,the substrate 101 may include at least one selected from the groupconsisting of carbon (C), iron (Fe), manganese (Mn), nickel (Ni),titanium (Ti), molybdenum (Mo), and stainless steel (SUS). The substrate101 may also be formed of an alloy, such as Invar, Inconel, or Kovar.However, the substrate 101 is not limited thereto, and may be formed of,for example, a metallic foil.

In order to planarize the substrate 101 and prevent impure elements fromdiffusing into the substrate 101, a buffer layer 102 may be formed onthe substrate 101. The buffer layer 102 may be formed of, for example,SiO₂ and/or SiN_(x).

A thin film transistor (TFT) is formed on the buffer layer 102. Eachpixel of the OLED apparatus 100 includes at least one TFT that iselectrically connected to the intermediate layer 112. In FIG. 1, forconvenience of explanation, only one TFT is illustrated. However, thenumber of TFTs is not so limited, and each pixel may include a pluralityof TFTs.

In more detail, the active layer 103 forms a predetermined pattern onthe buffer layer 102. The active layer 103 may be formed of an organicsemiconductor, or an inorganic semiconductor, such as amorphous silicon,or polysilicon. The active layer 103 includes a source region, a drainregion, and a channel region.

The source and drain regions may be formed by doping an impurity intothe active layer 103. A P-type semiconductor may be obtained, if theactive layer 103 is doped with a group 13 element, for example, boron(B), and an N-type semiconductor may be obtained if the active layer 103is doped with a group 15 element, for example, nitrogen (N).

A gate insulating film 104 is formed on the active layer 103. The gateelectrode 105 is formed on a portion of the gate insulating film 104.The gate insulating film 104 is used to insulate the active layer 103from the gate electrode 105 and may be formed of an organic material oran inorganic material, such as SiN_(x) or SiO₂.

The gate electrode 105 may be formed of a metal, such as gold (Au),silver (Ag), copper (Cu), Ni, platinum (Pt), palladium (Pd), aluminum(Al), or Mo; or an alloy, such as an Al:Nd alloy or an Mo:W alloy.However, the gate electrode 105 is not limited thereto, and may beformed of various materials, in consideration of the adhesion withneighboring layers, the planarization of stacked layers, the electricresistance, the proccessability thereof, and so on. The gate electrode105 is connected to a gate line (not shown) that applies on/off signalsto the TFT.

An overcoat film 106 including contact holes is formed on the gateelectrode 105. The overcoat film 106 may be an organic insulating filmor an inorganic insulating film containing an oxide or a nitride.

The inorganic insulating film may be formed of SiO₂, SiN_(x), SiON,Al₂O₃, TiO₂, Ta₂O₅, HfO₂, ZrO₂, barium strontium titanate (BST), or leadzirconate titanate (PZT), for example. The organic insulating film maybe formed of a commercially available polymer, such aspolymethylmethacrylate (PMMA) or polystyrene (PS), a polymer derivativecontaining a phenol group, an acryl-based polymer, an imide-basedpolymer, an arylether-based polymer, an amide-based polymer, afluorine-based polymer, a p-xylene-based polymer, a vinyl alcohol-basedpolymer, or a mixture thereof, for example. The overcoat film 106 mayhave a stacked structure, in which the organic and inorganic films arestacked on one another.

Unlike a typical interlayer insulating film, the overcoat film 106 isplanar, because one of the source and drain electrodes 107 and 108operates as a pixel electrode. The intermediate layer 112, on which animage may be displayed, is formed on the pixel electrode. If theintermediate layer 112 is not planar, image quality is reduced.According to the current exemplary embodiment of the present invention,a lower surface of the intermediate layer 112 may be planarized, byforming the overcoat film 106 thereon.

The source and drain electrodes 107 and 108 may respectively contact thesource and drain regions of the active layer 103, through the contactholes. One of the source and drain electrodes 107 and 108 has anextended portion, which allows it to operate as a pixel electrode.According to the current exemplary embodiment of the present invention,the drain electrode 108 is shown as having the extended portion, whichcontacts the intermediate layer 112. The drain electrode 108 may bereferred to as a pixel electrode. However, the present invention is notlimited thereto, and the source electrode 107 may instead have such anextended portion, so as to operate as the pixel electrode.

The source and drain electrodes 107 and 108 may be formed of a metalsuch as Au, Pd, Pt, Ni, rhodium (Rh), ruthenium (Ru), iridium (Ir),osmium (Os), Al, or Mo; or a metal alloy such as an Al:Nd alloy or anMoW alloy. Each of the source and drain electrodes 107 and 108 may havea layered structure, in which a transparent conductive layer is formedon a reflective metal layer. The drain electrode 108 will be describedin detail, with reference to FIG. 2.

Referring FIG. 2, the drain electrode 108 includes first and secondlayers 108 a and 108 b. The first layer 108 a contacts and extends fromthe active layer 103, and the second layer 108 b is formed on the firstlayer 108 a and extends orthogonally therefrom.

The first layer 108 a may be a reflective conductive film, and thesecond layer 108 b may be a transparent conductive film. The reflectiveconductive film may be formed of a metal such as Au, Pd, Pt, Ni, Rh, Ru,Ir, Os, Al, or Mo; or a metal alloy such as an Al:Nd alloy or an MoWalloy. The transparent conductive film may be formed of a materialhaving a high work function value, which includes at least one selectedfrom the group consisting of indium tin oxide (ITO), indium zinc oxide(IZO), zinc oxide (ZnO), and In₂O₃.

Referring back to FIG. 1, when each of the source and drain electrodes107 and 108 is formed from two layers, and thus, because a materialhaving a high work function value covers an upper surface of each of thesource and drain electrodes 107 and 108, the pixel electrode may operateas an anode electrode. According to the current exemplary embodiment ofthe present invention, a separate process for forming a pixel electrodeis not required.

Conventionally, both an interlayer insulating film to insulate the gateelectrode 105 from the source and drain electrodes 107 and 108, and apassivation film to cover the source and drain electrodes 107 and 108,are needed. However, according to the current exemplary embodiment ofthe present invention, only the overcoat film 106 is used. As such, theOLED apparatus 100 may be thinner and easier to manufacture.

The pixel defining layer 109 is formed on the source and drainelectrodes 107 and 108, so as to expose sides of the source and drainelectrodes 107 and 108. The pixel defining layer 109 includes anaperture to expose the extended portion of the drain electrode 108.

The pixel defining layer 109 may be formed of an inorganic materialincluding one selected from the group consisting of SiO₂, SiN_(x), SiON,and Al₂O₃. Since the pixel defining layer 109 is formed of an inorganicmaterial, metal patterns of a driving circuit unit, which are formed inthe same plane and of the same material as the source and drainelectrodes 107 and 108, are not damaged during a sealing process.

In more detail, according to the current exemplary embodiment of thepresent invention, one of the source and drain electrodes 107 and 108operates as the pixel electrode, and the source and drain electrodes 107and 108 contact the pixel defining layer 109. The metallic patterns ofthe driving circuit unit, at an edge of the OLED apparatus 100, are alsoformed at the same level and of the same material as the source anddrain electrodes 107 and 108, so as to contact the pixel defining layer109.

If the pixel defining layer 109 is formed of an organic material, themetallic patterns may be damaged by the organic material, during asubsequent encapsulating process. However, according to the currentexemplary embodiment of the present invention, the pixel defining layer109 is formed of an inorganic material, and thus, the metal patterns ofthe driving circuit unit are not damaged during the encapsulatingprocess. The spacer 111 is formed on the pixel defining layer 109 andexposes the pixel electrode through the pixel defining layer 109. Thespacer 111 may be formed of an organic material or an inorganicmaterial. For example, the spacer 111 may include one selected from thegroup consisting of an imide-based material, benzo cyclo butene (BCB),acryl, cytop, and perfluorocyclobutene (PFCB).

The intermediate layer 112 including an organic light emitting layer isformed on the drain electrode 108, which is exposed through the pixeldefining layer 109. The facing electrode 113 is formed on theintermediate layer 112. The facing electrode 113 may also be formed onthe spacer 111, so as to cover all pixels, and may operate as a cathodeelectrode.

If the OLED apparatus 100 is a top emission type, the facing electrode113 may be formed by depositing a metal having a low work functionvalue, such as Ag, magnesium (Mg), Al, Pt, Pd, Au, Ni, neodymium (Nd),Ir, chromium (Cr), lithium (Li), calcium (Ca), or a mixture thereof, andthen depositing a transparent conductive material, such as ITO, IZO,ZnO, or In₂O₃, on the metal.

If the OLED apparatus 100 is a top and bottom emission type, the sourceand drain electrodes 107 and 108, and the facing electrode 113 may betransparent. If the OLED apparatus 100 is a bottom emission type, thesource and drain electrodes 107 and 108 may be transparent, and thefacing electrode 113 may be reflective.

The intermediate layer 112 is disposed between the drain electrode 108and the facing electrode 113 and includes the organic light emittinglayer that generates visible light. The intermediate layer 112 emitslight, according to voltages applied to the facing electrode 113 and thedrain electrode 108.

The intermediate layer 112 may be formed of an organic material. If theorganic light emitting layer of the intermediate layer 112 is formed ofa low molecular weight organic material, a hole transport layer (HTL)and a hole injection layer (HIL) are stacked on one another, in adirection toward the drain electrode 108, with reference to the organiclight emitting layer. An electron transport layer (ETL) and an electroninjection layer (EIL) are stacked on one another, in a direction towardthe facing electrode 113. In addition to the above-mentioned layers,various other layers may be stacked. The low molecular weight organicmaterial forming the intermediate layer 112 may be, for example, copperphthalocyanine (CuPc), N,N′-Di(naphthalene-1-yl)-N,N′-diphenyl-benzidine(NPB), or tris-8-hydroxyquinoline aluminum (Alq₃).

Meanwhile, if the organic light emitting layer of the intermediate layer112 is formed of a polymer material, the HTL may be formed in adirection toward the drain electrode 108, with reference to the organiclight emitting layer. In this case, the HTL may be formed of, forexample, poly-(2,4)-ethylene-dihydroxy thiophene (PEDOT) or polyaniline(PANI), on the drain electrode 108, by using an inkjet printing methodor a spin coating method. The organic light emitting layer may be formedof, for example, polyphenylene vinylene (PPV), soluble PPV's, cyano-PPV,polyfluorene. A color pattern may be formed by using any suitablemethod, such as inkjet printing, spin coating, or laser-induced thermalimaging.

A sealing member (not shown) may be arranged to face one surface of thesubstrate 101. The sealing member protects the intermediate layer 112from external moisture and/or oxygen, and is formed of a transparentmaterial. The sealing member may be formed of a stack of differentmaterials, such as glass and plastic, or organic and inorganicmaterials.

FIGS. 3 through 13 are schematic cross-sectional views sequentiallyillustrating a method of manufacturing the OLED apparatus 100, accordingto an exemplary embodiment of the present invention. FIGS. 3 through 13will be described in conjunction with FIG. 1. Although the OLEDapparatus 100 illustrated in FIG. 1 will be referred to, in order todescribe the exemplary method, the aspects of the method may be appliedto other types of OLED apparatuses.

The method includes: forming the active layer 103 on the substrate 101;forming the gate electrode 105; forming the source and drain electrodes107 and 108; forming the pixel defining layer 109 on the source anddrain electrodes 107 and 108; forming the spacer 111 on the pixeldefining layer 109; forming the intermediate layer 112; and forming thefacing electrode 113.

Referring to FIG. 3, the buffer layer 102 is formed on the substrate101, and the active layer 103 is formed on the buffer layer 102. Thegate insulating film 104 is formed on the active layer 103, and the gateelectrode 105 is formed on the gate insulating film 104. As shown inFIG. 3, the active layer 103 is formed to have a pattern. The activelayer 103 may be formed using a photolithography method.

Referring to FIG. 4, the overcoat film 106 is formed, so as to cover thegate electrode 105. Contact holes are formed in the overcoat film 106,to expose source and drain regions of the active layer 103. The contactholes may be formed using photolithography.

Referring to FIG. 5, a conductive layer 107 a is deposited, which ispatterned to form the source and drain electrodes 107 and 108. Theconductive layer 107 a can be formed of the same materials as recitedabove for the source and drain electrodes 107 and 108. Although notshown, the conductive layer 107 a may be formed of two layers, such asthe first and second layers 108 a and 108 b illustrated in FIG. 2.

Referring to FIG. 6, an inorganic layer 109 a is deposited on theconductive layer 107 a. The inorganic layer 109 a can be formed of thesame materials as described above for the pixel defining layer 109.

Referring to FIG. 7, a photo resist P and a halftone mask HM areprepared, for use in performing a photolithography method. The halftonemask HM includes a light transmission unit HM1, a light blocking unitHM2, and a half transmission unit HM3.

The light transmission unit HM1 transmits light of a predeterminedwavelength range, the light blocking unit HM2 blocks projected light,and the half transmission unit HM3 transmits only a portion of theprojected light. The halftone mask HM is arranged on the substrate 101,in order to pattern the photo resist P. Light is projected on thesubstrate 101, through the halftone mask HM.

The photo resist P is illustrated in FIG. 8, after the light isprojected. For convenience of explanation, a positive photo resist (PR)will now be exemplarily described as the photo resist P. However, thepresent invention is not limited to the positive PR, for example, anegative PR may be used.

Referring to FIG. 8, a portion corresponding to the light transmissionunit HM1 is removed from the photo resist P, and a portion P2corresponding to the light blocking unit HM2 and a portion P3corresponding to the half transmission unit HM3 remain. In this case,the portion P3 is thinner than the portion P2.

Referring to FIG. 9, the conductive layer 107 a is etched according tothe pattern of the photo resist P, so as to form the source and drainelectrodes 107 and 108. The inorganic layer 109 a is also etched, so asto form an inorganic pattern 109 b corresponding to the source and drainelectrodes 107 and 108. In this case, one of the source and drainelectrodes 107 and 108 includes an extended portion, so as to operate asa pixel electrode. According to the current exemplary embodiment of thepresent invention, the drain electrode 108 has the extended portion.

Referring to FIG. 10, the portion P3, corresponding to the halftransmission unit HM3, is removed. Thus, a portion of the inorganicpattern 109 b is exposed, and only the portion P2, corresponding to thelight blocking unit HM2, remains. In this case, an upper surface of theportion P2 may be etched to reduce the thickness thereof. The aboveprocess may be performed using an ashing process, without an additionalmask.

Referring to FIG. 11, the exposed portion of the inorganic pattern 109 bis etched, so as to form the pixel defining layer 109 having theaperture. The portion P2 is then completely removed.

Referring to FIG. 12, the spacer 111 is formed, so as to expose theaperture of the pixel defining layer 109. Photolithography may be usedto pattern the spacer 111.

Referring to FIG. 13, the intermediate layer 112 is formed on theextended portion of the drain electrode 108, which is exposed throughthe aperture of the pixel defining layer 109. The intermediate layer 112includes an organic light emitting layer. The facing electrode 113 isthen formed on the intermediate layer 112.

Although not shown, a sealing member (not shown) may be arranged to faceone surface of the substrate 101. The sealing member protects theintermediate layer 112 from external moisture and/or oxygen, and isformed of a transparent material, as described above.

According to the current exemplary embodiment of the present invention,one of the source and drain electrodes 107 and 108 has an extendedportion and operates as the pixel electrode, such that an additionalprocess is not needed to form the pixel electrode. In particular, aphotographic process for patterning the pixel electrode is not required,to simplify manufacturing and lower a defect rate thereof. Also, thesource and drain electrodes 107 and 108 and the pixel defining layer 109may be formed using a single halftone mask HM.

FIG. 14 is a schematic cross-sectional diagram of an OLED apparatus 200,according to another exemplary embodiment of the present invention.Referring to FIG. 14, the OLED apparatus 200 includes a substrate 201,an active layer 203, a gate electrode 205, a source electrode 207, adrain electrode 208, a pixel defining layer 209, a spacer 211, anintermediate layer 212, a facing electrode 213, a first capacitorelectrode 253, and a second capacitor electrode 255.

Elements of the OLED apparatus 200, other than the first and secondcapacitor electrodes 253 and 255, are similar to the elements of theOLED apparatus 100. Thus, a detailed description of the similar elementsis omitted.

A buffer layer 202 may be formed on the substrate 201. The active layer203, which is patterned, is formed on the buffer layer 202.

The first capacitor electrode 253 is formed on the buffer layer 202, ofthe same material as the active layer 203. The active layer 203 and thefirst capacitor electrode 253 may be simultaneously patterned using asingle mask.

A gate insulating film 204 is formed on the active layer 203. The firstcapacitor electrode 253, the gate electrode 205, and the secondcapacitor electrode 255 are formed on the gate insulating film 204.

The second capacitor electrode 255 is formed of the same material as thegate electrode 205. The gate electrode 205 and the second capacitorelectrode 255 may be simultaneously patterned, using a single mask.

According to the current exemplary embodiment of the present invention,the first and second capacitor electrodes 253 and 255 may be formedwithout using additional masks. The active layer 203 and the firstcapacitor electrode 253 are formed in the same plane, and the gateelectrode 205 and the second capacitor electrode 255 are formed in thesame plane. Therefore, additional layers for the first and secondcapacitor electrodes 253 and 255 may not be required. Thus, thethickness of the OLED apparatus 200 is reduced.

The first and second capacitor electrodes 253 and 255 are formed belowan extended portion of the drain electrode 208. As such, a top emissionstructure may prevent a reduction in aperture ratio and luminance. Abottom emission structure may prevent a reduction in aperture ratio andluminance, by forming the first and second capacitor electrodes 253 and255, so as not to correspond to the extended portion of the drainelectrode 208.

According to the current exemplary embodiment of the present invention,one of the source and drain electrodes 207 and 208 has an extendedportion, and operates as a pixel electrode, such that an additionalprocess for forming the pixel electrode is not required. In particular,thin films for forming the pixel electrode, such as a conductive layerand an insulating layer, are not required, and thus, the thickness ofthe OLED apparatus 200 may be relatively reduced.

Although not shown, the method described above with reference to FIGS. 3through 23 may be used to manufacture the OLED apparatus 200. Thus, thesource and drain electrodes 207 and 208 and the pixel defining layer 209may be formed using a single halftone mask.

Although not shown, a sealing member may be arranged to face one surfaceof the substrate 201. The sealing member is transparent and protects theintermediate layer 212 from external moisture and/or oxygen. The sealingmember may have a similar structure to the previously described sealingmember. According to aspects of the present invention, a thin OLEDapparatus may be more easily manufactured.

Although a few exemplary embodiments of the present invention have beenshown and described, it would be appreciated by those skilled in the artthat changes may be made in these exemplary embodiments, withoutdeparting from the principles and spirit of the invention, the scope ofwhich is defined in the claims and their equivalents.

What is claimed is:
 1. A method of manufacturing an organic lightemitting display (OLED) apparatus, the method comprising: forming anactive layer on a substrate; forming a gate electrode on the substrate,so as to be insulated from the active layer; forming a first electrodeon the substrate, so as to be insulated from the gate electrode and beelectrically connected to the active layer, the first electrode havingan extended portion that operates as a pixel electrode; forming a secondelectrode on the substrate, so as to be insulated from the gateelectrode and be electrically connected to the active layer; to forminga pixel defining layer on the source and drain electrodes, the pixeldefining layer having an aperture that exposes the extended portion;forming an intermediate layer comprising an organic light emittinglayer, in the aperture and connected to the extended portion; andforming a facing electrode on the intermediate layer, wherein one of thefirst and second electrodes is a source electrode, and the other is adrain electrode.
 2. The method of claim 1, wherein the pixel defininglayer comprises an inorganic material.
 3. The method of claim 1, furthercomprising forming an overcoat film on the gate electrode, before thefirst and second electrodes are formed, to insulate the gate electrodefrom the first and second electrodes.
 4. The method of claim 1, furthercomprising forming a spacer on the pixel defining layer, which has anopening to expose the aperture, before the intermediate layer is formed,wherein the forming of the facing electrode comprises forming the facingelectrode on the spacer, such that the facing electrode is separatedfrom the pixel defining layer.
 5. The method of claim 1, wherein: theforming of the active layer further comprises forming a first capacitorelectrode in the same plane and of the same material as the activelayer, and the forming of the gate electrode further comprises forming asecond capacitor electrode that is insulated from the first capacitorelectrode, on the first capacitor electrode, in the same plane and ofthe same material as the gate electrode.
 6. The method of claim 5,wherein the first capacitor electrode faces the extended portion.
 7. Themethod of claim 1, wherein the extended portion of the first electrodeextends away from the second electrode and faces the intermediate layer.